Why is that a big deal, or even needed? Here’s why:
Michael Crumling, a 25-year-old machinist from Pennsylvania in the United States, has developed a round designed specifically to be fired from 3D printed guns. His ammunition uses a thicker steel shell with a lead bullet inserted an inch inside, deep enough that the shell can contain the explosion of the round’s gunpowder instead of transferring that force to the plastic body or barrel of the gun. Crumling says that allows a home-printed firearm made from even the cheapest materials to be fired again and again without cracking or deformation. And while his design isn’t easily replicated because the rounds must be individually machined for now, it may represent another step towards durable, practical, printed guns-even semi-automatic ones.
More at the link.